Human leukocyte antigen A2 or A3 (HLA-A2 (for allele *A*02) and HLA-A3 (for allele *A*03))

Human leukocyte antigen A2 and A3 are polymorphic cell surface proteins belonging to the major histocompatibility complex class I family. They are encoded by separate alleles at the HLA-A locus, and are responsible for presenting short peptide fragments—derived from endogenous proteins or intracellular pathogens—to cytotoxic T lymphocytes. This interaction is a cornerstone of immune recognition, driving the destruction of infected, mutated, or foreign cells by the host immune system. HLA-A2 and HLA-A3 differ in their peptide-binding motifs and genetic sequence, which impact immune responses and clinical outcomes in transplantation, infection, and cancer. Both are of major focus in immunotherapy and vaccine design, owing to their high prevalence and functional importance in human health and disease.

Other names

HLA-A*02 (or HLA-A2)HLA-A*03 (or HLA-A3)HLA-A supertypesA2 supertypeA3 supertype

Peptide presentation for cytotoxic T cell activation Allow drugs or therapies to target antigen expressed in context of HLA-A molecule (e.g., specific TCR interaction with HLA-A2-presented tumor antigen enables cell killing)